Waterproof plaster-board and method of making same



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muted Dec. 23, 1919.

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JAMES P. SEXTON, OF LOS ANGELES, CALIFORNIA.

WATERPROOF PLASTR-BOARD AND METHOD 0F MAKING SAME.

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i To all whom it may concern Be it known that I, JAMES P. SEXTON, acitizen of the United States, residing at Los Angeles, in the county ofLos Angeles, State of California,lhave invented new and usefulImprovements in Waterproof Plaster-Board and Methods of Making Same, ofwhich the following is a specification.

This invention relates to plaster board, plaster lath, and likearticles, which comprise a body of plaster or other plastic orcementitious substance and one or more facing sheets of paper or thelike; and the invention further articularly relates to such an articlein which the paper facing sheets are waterproofed.

Accordlng to my invention the paper facing` sheets may 'be waterproofedin any desired manner; in a typical case, as hereinafter described, theymay previously be waterproofed with a bituminous substance, such as tar.1n typical instances I use what is commercially known as tarred paper ortarred felt; being preferably a soft finished, tarred paper, in whichthe aper is thoroughly impregnated with tie waterproong substance. f

lln the use of such waterproofed papers, it has been impracticab-le orimpossible to join the plastic substances with the waterproofed paper.The very fact that the paper 1s waterproofed makes it Very difficult toform a bond between the moist plastic substance and the paper. This isparticularly true where the plaster is not bonded to the paper by amechanical bond of some sort. 1Where the paper and plaster aremechanically bonded, a waterproofed paper can, and has been, and is now,usedy by me in such construction yas is shown by my Patent No.1,115,593, November 3, 1914, and reissued June 5, 1916, No. 14,148., andshown also in the following named patents:v plaster lath, No. 1,205,399,Nov. 21, 1916; plaster lath, No. 1.205,360, November 21, 1916; andapplications as follows: method of making plaster lath, S. N. 129,650,Nov. 6, 1916; plaster lath, S. N. 187 ,331, Aug. 21, 1917.

1n such forms as herein referred to, one or both of the face sheets maybe mechanically bonded. And my present invention may be applied to suchmechanically bonded structure as Well as to a plain plaster board or thelike.

For the purpose of fully explaining my present invention I illustrateherewith, in

Specication of Letters Patent.

Patented Dec. 23, 1919.'`

Application mea December 19, 191%. serial No. 207,856.

the accompanying drawings, a plain plaster board and a plaster lathwhich is known commercially as buttonlath; Figure 1 belng a sectionshowing the structure of a plam plaster board; and Fig. 2 being asimilar structure showing the structure of suelta plaster lath.

Such plaster boards and plaster laths are commonly made by interposingabody 10 of plastic substance between two sheets of paper or otherfibrous substance, shown at 11 and 12. In the case of the plainplasterboard, both these sheets 11 and 12 are plain papers; while in thecase of the plaster lath both facing sheets may be in the form shown at12 in Fig. 2, with apertures at 12, allowing protuberances or buttons10a to be formed of the plaster body 10; or one of the sheets may be inthis apertured form and the other, as shown at 11, may be in plain form.Regardless of any peculiar shaping of the facing sheets, and whether ornot there is a mechanical bond between the plaster and the sheet, mymethod of bonding the waterproofed sheet to. the plastic body may beused.

It is now the common practice to manufacture such plaster boards and theplaster laths by continuously laying a layer of moist or unstableplastic or similar substance upon a contlnuous length of paper and thenlaying another continuous length of paper over the plastic layer;suitable pressure being applied to press the plastic layer out into auniform thickness. The papers used may be waterproofed in any manner,preferably waterproofed with a substance which melts or becomes soft ata fairly low temperature. Also, although this is not necessary, for thepurpose of my invention the paper is preferably a relatively softrough-surfaced paper, and is waterproofed with a bituminous substance.Now, as hereinbcfore stated, under ordinary circumstances the moist orunstable plastic substance which is laid between the sheets of suchpaper will not incorporate with the paper owing to the waterproofquality of the same. But I cause such incorporation to be made bysuitably heating the plasterboard or plasterlath, either at the time offormation or at some time subsequent. Although I may cause the heatingto take place during setting, I prefer to heat after partial or completesetting or during the latter stages of setting. I heat the plaster boardor plasterlath to a temperature which is sufficient to cause thesoftening or melting of the bituminous waterproofing substance, butwhich is below the calcining temperature of the laster; and thistemperature is typically a out 130o to 150 F. That is, this temperatureis sufficient to cause the waterproofing substance to soften or melt,but it is not sulicient to deteriorate the plastic body. Heat of thisdegree of temperature need only be applied forca short 1nterval; it doesnot need to be ap lied during the whole of the setting or rying oeration of the plaster. By causing t e waterproofing substance to softenor melt, the pores in the paper are opened up so that (where the heatingis done before the plaster sets) the moist or unstable plastic substancemay permeate the paper to a certain extent by entering such ores; and(whether the heating is done be ore or after setting of the plaster) themelted or soft Waterproofing substance also penetrates the plasticsubstance to a certain extent. The substances are then allowed to cool,or cool and set, in their inter-permeated state. And by this means abond is formed between the plastic body and the?- waterproofed paperfacing, which bond 'extends over the whole of the surfaces of the bodyand paper, and causes the body and paper to be most thoroughlyincorporated and bonded together. When the body and paper sheets areonce bonded in this manner, the bond is as strong as or stronger thanthe plastic bod or the paper sheet itself. In fact, it is a mostimpossible to tear the paper sheet from the body without breaking ortearing one or both.

The foregoing description applies more particularly to the use of paperwhich has been previously waterproofed with a suitable substance. But itis not necessary that the paper be waterproofed before the application,of the plastic or cementitious substance thereto, as such waterproofingcan be made to take place during the process offormation of the plasterboard or the like. For instance,I have found it possible to rovide aplastic substance which, while it orms the body of the laster board,oont-ains in it a waterproo v g substance, such as certain kinds ofglue, or bituminous substance or the like, which melt or soften uponheating and which will permeate the outer paper sheets. For instance, agreasy waterproofing substance may be used, in this instance, or in theinstance heretofore explained in this specification, said substancesoftening or liquefying upon being heated and permeating the paper; andthen, when solidifying, forming the same kind of bond between the paperand the plastic body as is hereinbefore explained.

It will -be seen that my invention is primarily a method of bondingwhich may bo applied to any form of plaster board or plasterlat-h, etc.,Whether composed of one or more lastic bodies or sheets, and regardlessof t e shape, etc., of those sheets. Applied to a plain plaster board itcauses a thorough bond to be made where heretofore it has beenimpossible or highly diiiicult to make such a bond.; applied to aplaster latli .in which there is a mechanical bond, it adds itseffectiveness by providing a bond which is co-extensive with the paperand plaster.

I do not limit my invention to the particular details herein describedexcept as is `indicated by the following claims which are intended tocover the invention in its broad \as well as its specific aspects.Having described a preferred form of my invention, I claim:

1. The herein described method of making a waterproof plaster board orthe like, which comprises the placement of an unstable plastic substancein contact with a porous sheet waterproofed with a material which issoftened by heat and to which the cementitious substance is permeableand heating them to a temperature sufficient to soften the waterproofingof the sheet, to allow the waterproofing and the plastic substance tointer-permeate, and then allowing them to cool and set.

2. The herein described method of making a waterproof plaster board orthe like, which comprises the placement of an unstable plastic substancein contact with a porous sheet waterproofed with a material which issoftened by heat and to which the cementitious substance is permeableand heating them to a temperature sufficient to soften the waterproofingof the sheet but insulicient to deteriorate the plastic substance toallow the waterproofing and the plastic substance to inter-permeate, andthen allowing them to cool and set. i

3. The herein described method of making a waterproof plaster board orthe like, which comprises the placement of a moist plaster in contactwith a sheet impregnated with a bituminous substance, and heating themto a temperature sufficient to soften said bituminous substance andinsuicient to calcine the laster to allow the softened substance and t emoist plaster to inter-permteate, and then allowing them to cool and se4. The herein described method of bonding a cementitious substance and asheet waterproofed with a substance softened or melted by heat and towhich the cementitious substance is permeable, which comprises placingthe substance and sheet in contact, heating them to soften thewaterprooffing substance to allow it to permeate the cementitioussubstance, and then allowing them to cool.

5. The herein described method of bonding a plaster and a paperimpregnated with bituminous substance, which comprises placing theplaster in contact with the paper, and heating them to a temperaturesufficient to soften the bituminous substance but insufficient tocaloine the plaster.

6. The herein. described method of making a Waterproof plaster board orthe like, Which comprises the placement of a water proofing capable ofbeing softened by heat and an unstable plastic material which ispermeable to the softened Waterproofing material in contact with a sheetpermeable to the-softened Waterproofing material, and heating them to atemperature suiicient to soften the Waterproofing, to allow theWaterprooing to permeate the plastic material vthe plaster and thebituminous substance being incorporated by interpenetration with eachother over their face of contact.

In witness that I claim the foregoing I have hereunto subscribed my namethis 4th day of December, 1917.

JAMES P. SEXTON. Witness:

V. BERINGER.

